#define _CRT_SECURE_NO_WARNINGS
#include <iostream>

using namespace std;

class Solution {
public:
    int tribonacci(int n) {
        if (n == 0)
        {
            return 0;
        }
        if (n == 1 || n == 2)
        {
            return 1;
        }

        int a = 0, b = 1, c = 1, d = 0;
        for (int i = 3;i <= n;i++)
        {
            d = a + b + c;
            a = b;
            b = c;
            c = d;
        }
        return d;
    }
};

int main()
{
	return 0;
}